Process of manufacturing white lead.



Patented Feb. 25, 1902.

F. J. CURBETT. PROCESS OF MANUFACTURING WHITE LEAD.

(Application filed June 9, 1900.) (No Model.) 2 Sheets-Sheet I.

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Nu. 694,l38. Patented Feb; 25, I902.

F. J. conssn.

PROCESS OF MANUFACTURING WHITE LEA D.

(Amilication filed June 9, 1900.

.(lo Iflodel.) 2 Sheets-$heet 2.

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UNITED STATES PATENT EErcE.

FREDERICK JOHN OORBETT, OF PRAHRAN, VICTORIA, AUSTRALIA.

PROCESS OF MANUFACTURING WHITE LEAD.

SPECIFICATION formingpart at Letters Patent No. 694,138, dated February25, 1902.

Application filed .Tune 9, 1900. Serial No. 19,661. (No specimens.)

To all whom it may concern.-

Be it known that I, FREDERICK JOHN Con-- BETT, a subject of the King ofGreat Britain and Ireland, residing in the city of Prahran, county ofBourke, State of Victoria, Australia, have invented certain new anduseful Improvements in Processes of Making White Lead, of which thefollowing is a specification.

The object of this invention is to provide a cheap and rapid process forthe manufacture of whitelead and one which can be carried on in a closedapparatus,so as to be non-in j urious to health. For this purpose theinvention consists of the process herein described of making white lead,which comprises the steps of mixing aldehyde and acetic acid insubstantially the proportions specified, introducing lead oxid into thesolution, agitating the mixture, simultaneously subjecting the same tocontact with carbonic-acid gas, permitting the mass to settle, drawingofi the supernatant liquid, and heating the precipitate to a temperaturesuiflcient to expel the liquid remaining therein.

In the accompanying drawings, Figure 1 is a front view, with partsbroken away, of an apparatus in which my improved process can be carriedout. Fig. 2 is a side view of the apparatus, also with parts brokenaway; and Fig. 3 is a detail section through one of the floats of theapparatus.

Similar letters of reference indicate corresponding parts.

Referring to the drawings,Aindicates an upper reservoir, whichcommunicates by a pipe a, having a valve a,with a carbonatin g chamber0, provided with an agitator c, journaled therein, and of any suitableform for agitating the contents of the chamber.

B is a hopper provided with a dischargetube b and valves 1) 6 saiddischarge-tube communicating at its lower end With thecarbonating-chamber. The valves U12 are connected by a handled leverbipivoted at a point between said valves to a post b on the tube b, sothat said valves can be simultaneously operated in opposite directions.

From the lower part of the carbouatingchamber extends a pipe 0, having avalve 0 and communicating with the interior of a settling-vat D. Theupper part of the carbouating-chamber is connected by a valved pipe nwith the upper part of the vat D. Two of these vats, with theirconnecting-pipes c'n, are arranged as shown in Fig. 1. Within each vatis arranged a float d, counterbalanced by a weight d, which is connectedwith the float by awire d passing through the top of tho vat D and overa pulley d mounted rotatably upon an arm 7' of a standard 1", risingfrom the floor R or from any other point of support. To the float isconnected a flexible siphon-pipe e of rubber or other suitable material,located within the vat D. The float cl is made of wood or other suitablematerial of sufficient lightness as to float upon the surface of theliquid employed and is provided with a bore d, extending through thesame. A coupling d connects the pipe 6 with said bore, said pipe beingby the bore placed in communication with the portion of the vat belowthe float. The upper end of the flexible tube e is connected with avalved pipe e, which passes through the wall of the vat at the upperpart of the same and thence iu downward direction, its lower end beingconnected with the spout g of a suitable distilling-pan Gr. Each vat Dis connected at its lower end by a suitable valved pipe g with saidvacuum-pan G, and the latter is provided at its interior with anagitator G of any suitable construction, the shaft g of said agitatorbeing journaled at its lower end in, a cross-bar g? of the pan and atits upper end in a cap g of the spout g of the pan and provided outsideof the same with a bevel-gear g or other means for operating the same,as shown in Fig. 1. The lower end of the vacuum-pan is connected by apipe t', having a valve 2', with pipes W, deliveringinto settlingvessels I. The wall of the pan is provided with observation-windows on.To the outer end of the spout g of the vacuum-pan is connected thecondensing-coil F, which is surrounded by a suitable liquid vessel, ifprovided with an overflow f, the whole forming a condenser for thevapors distilled off from the material in the pan. The lower end of thecoil F passes through the vessel f and delivers into a lowerliquid-reservoir A. This is a closed vessel, and from the upper portionof the same rises and then descends a pipe 0 into a vessel 0, filledwith glycerin or any other suitable material, thus forming a sealpermitting the escape of air or gas from the vessel A, but notpermitting ingress of the same through the pipe 0. To the coil F belowits tankfis connected by the pipe f an air-pump E, which pump alsocommunicates by pipe f with the tank A. From the upper portion of saidtank A a pipe a runs directly to the upper liquid reservoir A, and fromthe lower portion of said tank A a pipe a communicates with the pump E,and another pipe a connects said pump with the upper reservoir A.

For carrying out my improved process in this apparatus a solution offrom thirty to ninety per cent. of aldehyde and seventy to ten per cent.of commercial acetic acid of thirty-five-per-cent. strength is placed inthe upper reservoir A. In case as low as thirty per cent. of aldehyde isused a part of the balance will be made up of waterthat is to say, theentire seventy per cent. remaining will not consist of acetic acid, buta proportion of said seventy per cent. is preferably water. A quantityof this solution is allowed to flow from the reservoir A into thecarbonating-chamber, so as to fill the latter somewhat less than halffull. The hopper B having been filled with litharge, a quantity of thesame is permitted to flow through the discharge-tube b into thecarbonating-chamber, the valves 1) 19 serving to measure off thequantity admitted, and said quantity being sufficient so that with thesolution already in the chamber said chamber is filled approximatelyhalf full. The chamber 0 is provided at its upper portion with aninlet-tube t, communicating with valved branch tubes 25 25 Apressure-gage t is connected with said tubes between the valves i, so asto show the pressure in the chamber 0. The pipes t are connected withsuitable sources of carbonic-acid gas and compressed air, respectively.After all the cooks are closed on the carbonating-chamber the agitatoris started and carbonic-acid gas and compressed air allowed to .enterthe chamber for from thirty to sixty minutes, the time depending uponthe pressure employed of the gas. The mixing operation having beencompleted,the contents of the chamber are permitted to fiow through thetube a into one of the settling-vats D. Here the same is allowed tosettle, the solid matter, which may be termed the precipitate or sludge,settling to the bottom of the tank, while the liquid, which is the sameas the original liquid, it having undergone no change, standssupernatant upon the sludge. The valve 2 of the pipe e is opened, andthe air-pump E is started, whereby a suction is created in the pipe f,coil F, spout g, pipes e and e, and bore d so that the liquid in the vatD is drawn up through bore d and flexible tube 6 and flows down throughc, g, and the condensing-coil F, the whole forming a siphon, the actionof the pump E being continued, if necessary, to carry on the operation.The liquid of condensation is discharged by the coil F into the lowertank A. The sludge is now permitted to flow through the comparativelylarge connecting-tube g from the bottom of the settling-vat D into thevacuumpan G. The pan G is provided with a jacket G to which steam isadmitted by the valved supply-pipe k, which is connected with anysuitable source of steam. The valve e is.

closed and the pump E set in operation, so,

as to reduce the pressure within the pan. The spout g of the pan isprovided with a checkvalve so as to maintain the vacuum in the pan. Bythe heat and the reduction of atmospheric pressure, the remaining liquidin the sludge is rapidly and thoroughly driven off. The mass is agitatedby the agitator G, which facilitates the distilling operation. Whenreducing the pressure within the vacuum-pan, the air removed by the pumpE is drawnthrough the spout g, coil F, and pipe f and delivered throughpipe f into the tank A, from which it is forced by the succeedingquantity of air in outward direction through the pipe 0, escaping fromthe latter be low the level of the liquid in the vessel 0 and bubblingup through said liquid. The vapors of aldehyde and acetic acid, togetherwith whatever water-vapor there may be, condenses in the coil F, and theliquid collects in the tank A. The pump and agitator are stopped whenthe distilling operation is complete, and atmospheric pressure isrestored in the vacuum-pan by a suitable vent-cock a, such as shown atthe upper portion of the pan in Fig. 2. Oil is then admitted to the panthrough a suitable pipe 0. and the agitator again set in motion, so asto thoroughly mix the white lead with the oil. The quantity of oiladmitted depends upon the quantity of white lead in the pan G, and inany case is sufficient to render the mixture fluid enough to be drawnoff through pipes i 2' into the tanks I, where it is allowed to settleand is then removed for packing or use. The liquid collecting in thetank A is pumped, by means of the pump E, through pipes a a? up to thetank A for use again in the process. The vent-cock n of the chamber 0serves for restoring atmospheric pressure in the chamber prior to theadmission of another charge of litharge and solvent fluid. The pipe 11,with its valve n, afiordscommunication between the chamber'C and the vatD, so that any desired pressure of gas can be exerted on the surface ofthe mass in the Vat for assisting the discharge of the same through thetube g into the pan G when the valve 8 of said tube is opened.

The process has been described in connection with only one of thesettling-vats D. As a matter of fact, however, it is advantageous tooperate the two settling-vats-that is to say, charging'them alternatelyfrom the carbonating-chamber O and discharging them alternately into thevacuum-pan G. The time necessary for the settling of each charge in thesettling-tank is from three to six hours.

In place of aldehyde and acetic acid alcohol and acetic acid insubstantially the same proportions may be employed.

I am aware that heretofore processes have been proposed in whichlitharge or lead oxid was mixed with water and the mixture subjectedunder agitation to contact with carbonic-acid gas and the waterafterward expelled from the resulting white lead by heat. White lead,however, has a strong afiinity for water, and the complete removal ofall aqueous moisture from the white lead was a very diificult part ofsuch a process and required subjecting the white lead to heat for aconsiderable length of time. By my process, however, this objection isentirely overcome. The mixture of aldehyde and acetic acid is expelledfrom the white lead quickly and thoroughly, and high heat is notrequired. Furthermore, it is possible to employ with the aldehyde oralcohol and acetic acid a considerable proportion of water, for whilewater in itself is stronglyheld by white lead, as above referred to, thepresence of aldehyde or alcohol serves to neutralize this afiinity, sothat the water is entirely expelled from the white lead at a temperaturenot greatly exceeding the temperature required to expel the alcohol oraldehyde and acetic acid alone. A cheap and rapid process for theproduction of a superior quality of White lead is thus provided.

Having thus described my invention, I

claim as new and desire to secure by Letters Patent 7 1. The processherein described of making 7 white lead, which consists in mixingaldehyde and acetic acid in substantially the proportions specified,introducing lead oxid into the solution, agitating the mixture,simultaneously subjecting the same to contact with carbonic-acid gas,permitting the mass to settle, drawing off the supernatant liquid, andheating the precipitate to a temperature sufficient to expel the liquidremaining therein,

substantially as set forth.

2. 1 The process herein described of making white lead, which consistsin mixing aldehyde acetic acid and Water in substantially theproportions specified, introducing lead oxid into the solution,agitating the mixture, simultaneously subjecting the same to contactwith carbonic-acid gas, permitting the mass to settle, drawing oEE thesupernatant liquid, and heating the precipitate to a temperaturesufficient to expel the liquid remaining therein, substantially as setforth.

In witness whereof I have hereunto set my hand to this specification.

FREDERICK JOHN OORBETT.

In presence of- EDWIN PHILLIPS, CECIL W. LE PLASTRIER.

